COLUMBUS, OH -- Republican presidential candidate Donald Trump says the U.S. should engage in much more aggressive interrogation techniques on terrorism suspects as he continues to push a hard line on national security after the Paris attacks.

Speaking to thousands at a packed Columbus rally, Trump said techniques practiced until late in the Bush administration and disavowed by President Barack Obama should be brought back because they work.

That includes waterboarding, he said, a practice that simulates drowning. He said he'd restore waterboarding "in a heartbeat" and approve "more than that."

A Senate Intelligence Committee report last year concluded that harsh interrogation techniques failed to produce information that the CIA couldn't have obtained elsewhere or didn't already have. Republican leaders objected to the report's findings, as did some former CIA officials, who said they gained vital intelligence that still guides counterterrorism efforts.

Trump, who has been advocating a bullish - if vague - approach to foreign policy, declared, "Only a stupid person would say it doesn't work." He went on: "If it doesn't work, they deserve it anyway for what they're doing to us."

Trump had said a day earlier that he believed the U.S. should bring back enhanced interrogation techniques, including waterboarding, because they are "peanuts" compared with the torture methods used by the Islamic State group.

Trump also dug in his heels Monday over claims that he saw "thousands and thousands" of Muslims celebrating the 9/11 attacks in Jersey City. There is no evidence in news archives of mass celebrations by Muslims in Jersey City, as he alleged on the weekend.

He appeared to dial back his words slightly, saying he "saw people getting together and in fairly large numbers celebrating as the World Trade Center was coming down" both "on television and I read about on the Internet."

But Trump said he'd received hundreds of calls and tweets in recent days from people telling him they'd also witnessed the scenes he described.

As evidence, Trump cited a Sept. 18, 2001, story in The Washington Post that said in the hours after the attacks, authorities "detained and questioned a number of people who were allegedly seen celebrating the attacks and holding tailgate-style parties on rooftops while they watched the devastation on the other side of the river." The story did not suggest "thousands" were celebrating, as Trump has claimed, and a story the same day in The Star-Ledger in Newark, New Jersey, said the reports of such celebrations by Muslims proved unfounded.

Trump, who kicked off his first visit to Ohio with a Buckeyes football chant, also repeatedly mocked rival John Kasich, the state's governor, whose backers have launched an anti-Trump ad campaign and spent the day criticizing him before his visit.

Reciting his own dominant poll numbers, Trump told the crowd "your governor's" only at 2 percent.

"I heard he's dropping out," Trump cracked.

Earlier, Kasich supporters criticized Trump's tone and foreign policy know-how in a conference call with reporters and at a press conference.

"The recent attacks in Paris remind us that our country is in need more than ever of a leader who is qualified and experienced to understand and lead our military," said Tom Moe, who was a prisoner of war with Sen. John McCain in Vietnam.

Trump and Kasich have been feuding since last week, when New Day for America, a super PAC supporting Kasich, said it would spend $2.5 million on ads challenging Trump's readiness to be commander in chief.